Both sides of the fence

By David Brooks

Over the past decade there has been a rush of enthusiasm for fenced sanctuaries as a chance to offer a glimpse – albeit an incomplete one – of what New Zealand’s mainland environment was like before the destruction caused by introduced pests.

Fenced sanctuaries can eradicate almost all introduced predators from an area, allowing the return of native birds and other wildlife missing from the mainland for many decades.

But they have struggled financially and arguably sucked up funds that could have been used in more costeffective conservation work.

The excitement generated by projects like Zealandia and Maungatautari has generated proposals from other community groups for similar but usually smaller projects.

The enthusiasts involved have not always appreciated the huge investment in money and sweat required to make these projects work.

Pest-free offshore islands have been the last refuge for many of our most endangered species but access to many is restricted or difficult for people wanting to see these native treasures.

In the 1990s and early 2000s some bold thinkers suggested if we built fences and eradicated the pests within them, we could bring species such as saddlebacks (tieke), kaka, hihi, giant weta and tuatara to the Wellington suburbs or the middle of Waikato dairying country.

A tuatara at Zealandia, the first natural site on New Zealand’s mainland to reintroduce the reptiles. Photo: David Brooks.

The pioneer was Karori Sanctuary, since renamed Zealandia, where 225 hectares – mostly of regenerating bush – was fenced and 14 pest mammal species eradicated by January 2000.

A total of 47 threatened native plant and animal species have since been reintroduced. Little spotted kiwi, North Island saddlebacks, hihi, tuatara and Maud Island frogs have been returned to a natural mainland site for the first time.

“Being in the suburbs, we would not have been able to achieve what we have achieved if we were an unfenced project. We have animals that are here solely because we have a fence that keeps out pests,” Karori Sanctuary Trust Conservation Manager Raewyn Empson says.

In an article scheduled for publication in the June edition of the New Zealand Journal of Ecology, Canterbury Museum Curator of Vertebrate Zoology Paul Scofield and Resource Economics Professor Ross Cullen and Maggie Wang, both of Lincoln University,
argue that fenced sanctuaries offer poor value for money compared with other pest control regimes aimed at saving endangered species.

According to their study, there were at the end of 2006 a total of 18 completed or nearly completed fenced or partly fenced sanctuaries.

These included small areas aimed at protecting individual species such as Chatham Island black robins or skinks as well as eight fenced sanctuaries of 100ha or more aimed at protecting multiple species.

These 18 sanctuaries had a total of 109 kilometres of fencing protecting 7,133ha of habitat. The overall capital cost to the end of 2006 of these fences exceeded $24 million plus an estimated annual depreciation cost of $800,000 to reflect an estimated lifespan for the fences of 25 years, the study says.

Scofield and his colleagues quoted figures from an earlier study on kokako protection showing professional trapping and baiting protection work for these birds cost $115 to $155 a hectare annually.

Mainland islands – large open Department of Conservation reserves with intensive professional pest control – have annualised costs per hectare of $11 to $96. For fenced sanctuaries the mean cost per hectare was calculated at $3,365 a hectare in
the latest study.

“We believe that the rate of growth in predator-proof fence building is out of proportion to its benefits,” the authors say.

“We consider that in many cases the creation of sanctuaries enclosed by predator-proof fences is little more than the creation of expensive zoos surrounded by degraded habitat that will never be able to sustain the animal and plant species contained within the fence.”

The most imposing project so far is Maungatautari, where more than $20 million has been spent – with volunteer labour worth another estimated $10 million – since the project was launched in 2001 to enclose nearly 3,400ha within a 47km fence.

As well as financial strains, Maungatautari has recently been engulfed in a dispute over its governance structure, in which some local landowners have refused to allow the sanctuary’s staff and volunteers access to sections of the fence on their land.

The pioneering Zealandia-Karori Sanctuary in Wellington and the much larger Maungatautari Ecological Island in Waikato have blazed a trail for fenced sanctuaries. But some people question their value for money when conservation dollars are scarce.

Forest & Bird Advocacy Manager Kevin Hackwell says the conservation focus of a fenced sanctuary can be obscured by the financial strains.

“They have to keep raising money for maintenance and that keeps a lot of the focus of the sanctuary’s governors on raising money rather than having a focus on conservation.”

Building a fence does not mean the managers can forget about pests. “The actual effort in people power, going up and down the tracks doing the work is very similar whether you have a fence or not,” Hackwell says.

Mice remain a problem in fenced sanctuaries and there is a constant threat of the fence being breached by fallen trees or branches. Birds sometimes carry smaller pests into a sanctuary and weasels have twice been found inside Zealandia.

Fenced projects such as Zealandia and Maungatautari have attracted new donors to conservation but Scofield and Hackwell argue their financial problems inevitably suck up public money, through local or central government.

“I’m not aware of any of these big projects that haven’t had an absolute funding crisis and inevitably they end up turning to central and local government to rescue them.

Significant amounts of public money go into this and that money is lost to other conservation work,” Hackwell says.

An unfenced sanctuary offers more flexibility, especially if it lies within a wider expanse of bush.

Trapping and baiting regimes can be expanded or moved, whereas a fenced sanctuary remains defined by the area within the fence, though Empson points out Zealandia and some other fenced sanctuaries have pest control work going on outside their fences.

Forest & Bird and Auckland Council’s Ark in the Park open sanctuary in the Waitakere Ranges has expanded its core area to about 2,000ha from an original 250ha pilot area when the project started in 2003.

Further pest control work is done in buffer areas around the core.

When kokako released at the Ark during the past two years moved into bush outside the managed area, trapping and baiting was expanded into the birds’ new home, Ark Project Manager Maj De Poorter says.

The result over the past summer was the first successful hatching of kokako chicks in the Waitakeres for more than 80 years. [Fenced sanctuaries] have to keep raising money for maintenance and that keeps a lot of the focus of the sanctuary’s governors on raising money rather than having a focus on conservation.

Empson and Maungatautari Ecologist Chris Smuts-Kennedy agree fenced sanctuaries are more expensive and only one part of the overall conservation effort, but they say their goals are wider than pure conservation.

“It just depends on how much value people put on going to a place like Maungatautari or Karori and being able to see things they may not be able to see in a bait station or 1080 operation,” Smuts-Kennedy says.

“Your shopping list for reintroducing species is so much shorter if you are relying on a bait station operation rather than a fence.”

Some species are more vulnerable to even low numbers of pests and efforts to reintroduce saddlebacks to DOC’s Boundary Stream mainland island in Hawke’s Bay appear to have failed and hihi have struggled at the Ark in the Park.

Maungatautari has ambitions to eventually become the first mainland site to reintroduce kakapo, and Smuts-Kennedy says this bold step could only be contemplated at his sanctuary because of its size and absence of predators.

Even those who question the conservation value of fenced sanctuaries acknowledge they have an important role in educating and inspiring New Zealanders and visitors about our native wildlife.

But all those spoken to for this article agree that the rush of enthusiasm for fenced sanctuaries in the past decade has spawned several unrealistic proposals.

“There was a danger following our success at Karori that everyone wanted to get on the bandwagon,” Empson says. “I think all the local communities were saying we want one here. But there were not enough reality checks to ask ‘Is this the right place for it? Is this going to be big enough to do what you want to do?’ Another thing that was often
underestimated was the ongoing costs for these projects.”

Supporters of fenced sanctuaries say it is too early to make a judgement on their value because of their relatively short existence. “It’s a big experiment but really worthwhile,” says Landcare Research scientist John Innes. “I want to see the few that exist sustained and the monitoring of them done so they can be evaluated. It seems really silly to argue them down before the results are known.”

Everyone agrees there is no simple, single answer to achieving our conservation goals. “Any idea that there will be an alternative to bloody hard work is just false. In conservation there is no magical answer to any problem you have,” Scofield says.

What do you think about fenced sanctuaries? Are they a good showcase for our most
endangered native creatures? Who should pay for them? Is intensive pest control in unfenced areas a better long-term way of conserving native ecosystems? What’s best for the future?